Mast cell-mediated allergic inflammation is involved in many diseases such as asthma and sinusitis. Mast cells induce synthesis and production of pro-inflammatory cytokines including tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 with immune regulatory properties. In the present study, we investigate the effect an unspecified aqueous extract from leaves of Eriobotrya japonica Lindl. (Rosaceae) (LEJL) on the expression of pro-inflammatory cytokines and its possible mechanisms of action in human mast cells (HMC-1). LEJL dose-dependently inhibited phorbol 12-myristate 13-acetate (PMA) and calcium ionophore A23187 (PMACI)-induced gene expression and secretion of TNF-alpha, IL-6, and IL-8. LEJL attenuated PMACI-induced activation of nuclear factor (NF)-kappaB, and specifically blocked activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) but not that of c-jun N-terminal kinase. The inhibitory effect of LEJL on the pro-inflammatory cytokines was likely NF-kappaB, p38 MAPK, and ERK dependent. Our in vitro studies provide evidence that LEJL might contribute to the treatment of mast cell-derived allergic inflammatory diseases.